Thursday, September 8, 2011

Ultrasound data

On September 1st, the goats were scanned to determine rib fat thickness and rib eye area. The scanning was done by Jim Pritchard from West Virginia University.  The data were processed by the National CUP (Centralized Ultrasound Processing) Lab & Technology Center in Ames, Iowa.

For the goats in the pasture test, rib eye area ranged from 0.55 to 1.76 square inches and averaged 1.00 square inch.  While the data reveal genetic differences in carcass muscling, the biggest effect on rib eye area is weight.  Thus, the following table organizes the rib eye data according to the weight of the goats. 

In the report, ratios are used to compare a buck's rib eye measurement to the average for bucks in his weight range, e.g. 50 to 59 lbs. The buck with the largest rib eye (according to ultrasound) is #71, a Kiko buck consigned by Mark Sweitzer (PA). This buck's 1.76 square inch rib eye is 50 percent better than the average buck in his weight group (60-70 lbs.).  What's more impressive is that this buck's weight is at the low end of the weight range:  61 lbs.

Another buck with a high ratio is #33, a Savanna x Spanish buck consigned by Stephen & Janet Garrett (VA).  This buck's 1.46 square inch rib eye is 46 percent better than the average buck in the 50 to 59 lb. weight group.  Randy & Lolli Allen (TN) have another buck with a high ratio. The rib eye of #6, a 75% Kiko buck, measured 1.62 square inches, 38.5 percent better than the weight group average.

Rib fat thickness ranged from 0.01 to 0.08 inches and averaged 0.037 inches. The rib fat thickness measurements are largely meaningless, as when past carcass evaluations have been performed, none of the goats have had enough fat over the rib to measure it.  Body wall thickness is measured instead and is considered a better measure of carcass fat.

The rib area is clipped before scanning

Even the goats in the feed pen did not measure with much rib fat. Their rib fat thickness ranged from 0.04 to 0.07 inches and averaged 0.052 inches.  Unless they are "overfed," goats do not deposit much external fat. In fact, they fatten differently than other livestock, fattening from the inside-out.  The more important measure of fat in a goat is kidney and heart fat (internal fat), which can only be measured by harvesting the goats.

For the nine goats in the pen, rib eye area ranged from 0.70 to 1.78 square inches and averaged 1.23 square inches. The higher average can be attributed to the heavier weights of some of the bucks. The buck with the largest rib eye is a crossbred Spanish buck consigned by Karen Cooper (KY).

One of the objectives of the carcass evaluation is to compare the ultrasound rib eye measurements with those measured on the carcass.  Another objective is to compare carcass muscling between pasture and pen-fed goats.

The purpose of the pen feeding has been to create a contemporary set of goats for carcass evaluation -- not to compare their growth performance and resistance to parasites.

Download ultrasound report